Combination knife



' Sept. 29, 1953 D. T. TWISS COMBINATION KNIFE Filed Aug. 26, 1950 L UM ZSnventor DONALD 7'. 74055 Jm/ Gttorneg Patented Sept. 29, 1953 UNITED STATES PATENT OFFICE COMBINATION KNIFE iibnald Twiss, Los Angeles, Calif. Application August 26, 1950, SerialNo:1 8 1,60-3- 8 Claims. (01. 30--299) This. invention relates. to a combination knife and deals. more particularly with a knife structure of the type used by rooier's to cut sheet roof e in}; materials. The present knife structure may also be used to cut linoleum as well as other sheet materials. This application deals with a combination knife that is an improvement of the roofing knife disclosed in my pending application, Serial No. 149,227, filed March 13, 1950.

As explained in said pending application, conventional roofing knivesquickly all because of the 'attritive nature of the material out therea by. Such knives are provided with relatively thin blades that, moreover, have a cross-section al Wedge form-that tapers uniformly from a thicker heel part to a thin cutting edge. In said prior application, there are disclosed several forms of holder for 'a cutter mounted on the blade of a roofing knife. Whereas such forms depend on impinging engagement of a clamp screw against the blade to hold the cutter in place, the present invention contemplates and has for an object to provide clamping means, rather than a mount, to. clamp a cutter in adjustable position on the. knife blade.

Inasmuch as the cutter herein contemplated to be used is an alloy of tungsten, carbon and cobalt, a material sold under the trade name Carboloy and relatively expensive, it is another objector the invention to mount a relatively short length of said cutter material in a "holder and, in turn, clamp the holder in position.

Another object of the invention is to provide novel clamp elements which retain assembly with the knife blade while adjustment of the cutter is efiected, thus facilitating such adjustment and/ or replacement of the cutter. I

A further object of the invention is to provide clamp elements that are formed with diverging portions that define a throat in which the cutter is centrally disposed so that ravelings and fibers displaced by the cutter from the material being cut may be accommodated in said throat and not interfere with proper operation of the kriife.

The invention also has for its objects to pro- 'vi'de such means that are positive in operation, 'cen'v'enien't in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general-superiority and 'serviceabiilty.

"The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description.

2 However, the drawings merely show and the. rol lowing description merely describes one embediiment of" the present invention which is giilen' by way of illustration 'or example only.

In thedrawings, like reference charactersdesigjnate similar parts in thev several views.

Fig. 1 is a side elevational view of a generally conventional roofing knife provided with a cutter according to the present invention, the handle of the knife being broken away.

Fig. 2 is a vertical sectional View as, taken on line 2-2 of Fig. l.

Fig. 3 is a 'CTOSSr-SGCtiO-HEJ. view ast'aken online 3-3 of Fig. 1.

The blade 5. of the roofing knife has acutting edge 6 that is 'concavely formed to terminate a hook I. Oppo'sed to edge 6 is the dull backedge 8 and, as will :be bestseen from Fig. 2, the blade has a wedge form. According to the present invention, from the back edge 8 inward, he blade is provided with a preferably rectangular notch 9. Flanking said notch, there are provided holes 10. In this manner, blade 5 is initially prepared to receive the cutter H and the clamping means t2 therefor.

The cutter l I comprises a short; length of .Carboloy tool l3.-and-a holder 134 torming an upper extension of said tool. The tool is proyided with a sharp edge 15 that extends-along one longitu dinal'side edge and its upper end extends into a bifurcation [6 formed in the lower endof the tool "holder [4. The toolfand holder are brazed together to insure retention of assembly thereof. The width 'of the holder 14 is such as to have a sliding fit in notch 9 whereby the same is ireely adjustable insaidnotch. thickness of said holder is somewhat greater thanthat of the thickset portion of blade -5 as clearly illustrated in Figs. 2 and-3. Edge G'of blade 5 and edge P5 of cutter H are coplanar. v

The clamping means I 2 comprises t o similar but oppositely termed plates 41 that, at their lower ends, are each pro vided with an, outwardly angularly directed leg T81 that terminates in a laterall directed foot or gauge part it. The

- two legs l8 -of plates l"| diverge todefineathroat 2a, through the -middle of which cutter J| xtends as depicted in Fig.2. Oneplate (1 isprovided with holes {21 and the other with tapped holes 22 to register with holes in in blade I5'I'io'r clamp screws 23that fasten said plates 'toop positesides of said blade. 7 7

Each plate H is formed with'a vertical channel 24 that is quite shallow, the channels of both plates -cooperating to. engage the opposite sides of cutter holder M, as suggested in Figs. 2 and 3. In practice, these channels are of such shallowness that with the holder engaged between them, the lateral portions of plates ll are clear of the faces of blade 5. It will be clear, then, that when screws 23 are tightened, plates I! will have limited transverse flexure to insur tight clamping of the cutter holder. One or two backing turns on screws 23 will effect release of the clamping pressure on said holder to enable adjustment, as desired, of cutter H. Tightening of the screws will hold the adjustment.

The above-mentioned adjustment of the cutter is to obtain projection of tool l3 below the feet l9 so that said tool will cut to a desired depth as guided by said feet. Thus, as shown in Fig. 1, the upper of two sheets may be out without cutting into the lower sheet. It will be realized that reasonable accuracy of the depth of cut is desired even under conditions wherein the knife handle is presented at diiferent angles relative to the plane of the material being out. To insure reasonable uniformity of cutting depth, the cutting edge of the cutter I3 is arranged to bisect the middle of feet l9. In other words, said feet are arranged to be symmetrical relative to edge [5 rather than to the tool itself. Consequently, such small rocking of the knife that may occur during a cutting stroke will immaterially change the effective depth of out.

By offsetting the feet I9 to ali n with tool edge [5, the plates I! assume an elliptical shape that has a somewhat offset form presenting a trim, generally stream-lined appearance.

The non-clogging property of throat should be clear, since gravel, stone, etc. coating the sheet being cut and also displaced fibers of the sheet that may accummulate during a cutting stroke, are cleared without any tendency to raise the knife upward and disturb the depth of out.

It will be noted that the cutting edge 6 and hook I are not interfered with by the present novel improvement and that the same may be used when desired.

It will be seen that the end edge of the tool l3 has substantial width and is normal to cutting edge [5. This width of the tool is utilized as in cutting a sheet that varies in thickness, such as a shingle that has a wedge-shaped crosssection. In such work, the cutter is moved to its most projected position so that gauge feet [9 are most remote from the end of the cutter. Since the corner of the blade that is opposite edge l5 constitutes a heel on which the tool may be rocked, it will be evident that said edge 15 is raised or lowered relative to the heel so as to cut through thinner thicknesses when raised and thicker ones when lowered. Thus the cutter heel replaces the gauge feet 19 as the depth-gauging means of the tool.

While the invention that has been illustrated and described is now regarded as the preferred embodiment, the construction is, of course, subject to modifications without departing from the spirit and scope of the invention. It is, therefore, not desired to restrict the invention to the particular form of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

l. The combination with a knife blade having a slot formed therein and extending from the back edge thereof, of an elongated cutter adjustably extending into said slot and projecting beyond said back edge, the width of the cutter fitting said slot and the cutting edges of the blade and cutter being coplanar, and members on opposite sides of the blade and engaged with the opposite sides of the cutter to clamp the latter in adjusted position. v

2. The combination with a knife blade having a slot formed therein and extending from the back edge thereof, of a cutter adjustably extending into said slot and projecting beyond said back edge, members on opposite sides of the blade and engaged with the cutter to clamp the same in adjusted position, and laterally and oppositely directed portions on said members and constituting gauge means guiding the depth of cut of the cutter.

3. The combination with a knife blade having a slot formed therein and extending from the back edge thereof, of a cutter adjustably extending into said slot and projecting beyond said back edge, members on opposite sides of the blade and engaged with the cutter to clamp the same in adjusted position, laterally and oppositely directed portions on said members and constituting gauge means guiding the depth of cut of the cutter, and each member being provided with an outwardly angularly directed portion from the ends of which the oppositely directed portions extend, said angularly directed portions defining a throat in which the cutter is centrally disposed.

4. In a knife of the character described having a blade formed with a slot extending inwardly from the back edge of said blade, an elongated cutter adjustably positioned in said slot to extend beyond said back edge, the width of the cutter fitting said slot and the cutting edges of th blade and cutter being coplanar, and a pair of clamp members mounted on opposite sides of the knife blade and in clamping engagement with the opposite sides of that portion of the cutter that extends into the mentioned slot.

5. In a knife of the character described having a blade formed with a slot extending inwardly from the back edge of said blade, a cutter adjustably positioned in said slot to extend beyond said back edge, said cutter being thicker than said blade, a pair of clamp members on opposite sides of the knife blade, and clamp screws extending through the clamp members and knife blade on each side of the slot to tighten said members into clamping engagement with that portion of the cutter that extends into the slot.

6. In a knife of the character described having a blade formed with a slot extending inwardly from the back edge of said blade, a cutter adjustably positioned in said slot to extend beyond said back edge, and a pair of clamp members mounted on opposite sides of the knife blade and in clamp ing engagement with that portion of the cutter that extends into the mentioned slot, said cutter having a longitudinal cutting edge, and said clamp members being each provided with a laterally directed portion, said portions constituting a gauge to limit the depth of cut of the cutter.

7. In a knife of the character described having a blade formed with a slot extending inwardly from the back edge of said blade, a cutter adjustably positioned in said slot to extend beyond said back edge, and a pair of clamp members mounted on opposite sides of the knife blade and in clamping engagement with that portion of the cutter that extends into the mentioned slot, said cutter having a longitudinal cutting edge, and said clamp members being each provided with a laterally directed portion, said portions constituting a gauge to limit the depth of cut of the cutter, said gauge portions being arranged in symmetrical relation to said cutting edge of the cutter.

8. An elongated cutter tool comprising a shank of elongated form and of uniform width and of thickness, said shank having a longitudinal bifurcation along one end thereof, and a cutter blade comprising a length of hard wear-resistant material having substantially the same width as the shank and of a uniform thickness with one end of the blade fitted into said bifurcation, the end of the blade that resides in said bifurcation 6 being brazed to the shank. and one longitudinal edge of the blade being sharpened.

DONALD T. TWISS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,068,731 Blum July 29, 1913 1,434,047 De Bats Oct. 31, 1922 2,244,053 Comstock June 3, 1941 2,497,482 Wilson Feb. 14, 1950 FOREIGN PATENTS Number Country Date 38,936 Norway Feb. 11, 1924 

